Re: Proof of how Danzo was a disgrace to Konoha and Sarutobi:
The guy had many issues, the most obvious among those being an inferiority complex regarding Hiruzen and an almost obsessive desire to protect Konoha at all costs, but despite all that, he wasn't such a bad guy.
Like earlier posts have stated, Danzo was and may remain the most realistic character in Naruto, someone willing to sacrifice the lives of a few for the greater good of the many.
I hate it when people keep saying that everything he did was for himself. Sure, he may have done some unnecessarily selfish shit in order to get to the Hokage seat, but overall, his motives have always been the safety of Konoha.
* Killed the messenger frog during the Pain arc to ensure Naruto stayed away to prevent Pain from capturing him.
* Black-mailed the orphanage chick into working for him again to find out whether Iwa was a threat to Konoha's safety.
* Prevented his own ANBU from assisting in the defense of Konoha because he knew Tsunade would be able to protect it, even though mainly, it was for his own selfish purposes of attaining the Kage seat. Had there been any real danger, no doubt he would have acted.
That's the only things I could think of atm but I'm sure there's more.
Overall point is, sure the guy's a jackass, sure he's stepped over boundaries, but that's the kinda character Kishi made him to be, a focused protector of Konoha who did the dirty work from the shadows.
Also, for those who say that Hiruzen wasn't aware of Danzo's motives, you're all wrong. Hiruzen was more than aware of Root's existence and it's continued activeness. He also knew that Danzo was trying to take the Kage seat for himself but he didn't act on it, why? Because doing so would create strife within the ANBU and village plus, he knew that what Root was doing was essential to safety of Konoha.
As a character though, I still don't like him but I respect his goal of ensuring the continued survival of Konoha.